The present invention relates to a switching electrode portion of a circuit board for an electric watch. The invention also relates to a method of fabricating the switching electrode portion of the circuit board.
Electronic timepieces generally include a circuit board comprised of a base plate and metallic conductive circuit patterns formed thereon. Frequently, a switching electrode comprised of a conductive metallic layer will be formed on a narrow peripheral surface portion of the circuit board.
One technique for fabricating a switching electrode on an electronic timepiece circuit board includes forming a hole through a base plate of a circuit board, before the circuit patterns are formed. Next, metallic conductive material is plated through the hole. Finally, the base plate is cut in the final shape of the circuit board, and the line of cutting passes through the plated hole. The resulting circuit board therefore has a peripheral surface portion carrying a portion of the metallic conductive layer plated through the hole through the circuit board for defining a switching electrode.
One limitation of the prior art technique results when the cutting step is performed by press cutting. A cutting die used for press cutting causes the conductive metallic layer defining the switching electrode to lift off the circuit board base plate at the edges of the electrode. This is a serious problem since the portion of the electrode which lifts off the circuit board base plate may touch a switch and therefore cause faulty operation of the timepiece.